State of the art magnetic disk drives presently, and for some time have used a transducer carrying slider which flies over the media surface and is separated therefrom by a film of air. As recording densities become greater, the head is required to fly lower and the magnetic layer of the media becomes thinner. When the spacing between head and media is reduced from 25 or more microinches to fewer than ten microinches and the media magnetic layer thickness is reduced from as much as 50 to fewer than 5 microinches, the physical contact that occasionally occurs between head and media is of major concern.
To provide an acceptable rigid disk drive lifetime, the current technology employs a thin layer of a fluorocarbon lubricant applied to the magnetic medium during manufacture of the disk. This lubricant film is critically needed by the head/disk interface (HDI) to minimize wear to these components and significantly extend the lifetime of the disk drive to an acceptable level. A problem with this technology arises from depletion of the lubricant film with use. The loss of lubricant can be attributed to hydrodynamic ejection from the HDI due to air shear phenomena, thermal volatilization, thermal decomposition followed by bonding to the medium and lubricant spinoff.
These, and other wear processes at the HDI increase as the lubricant is lost and ultimately result in failure. The total wear to the HDI can be categorized into two distinct modes; first, a rapid wear rate that occurs during start/stop operations and second, a slower wear rate due to repeated high speed contacts at the HDI during normal file operations (disk at or near maximum speed). Wear associated with the start/stop process is only slightly dependent on head fly height, whereas for the latter case, a lowering of the fly height will dramatically increase the wear rate at disk drive operating speed (flyability). The increase for this latter case has been attributed to an increase in the collision frequency with disk asperities and debris (both foreign and from generated wear products). In this case, the presence of a lubricant film plays a critical role in protecting the HDI, but with the reduction in head fly height the lubricant film is also depleted more rapidly. Thus, for these reasons a reduction in flying height greatly increases the likelihood of early disk drive failure. The reason for reducing head flying height is to obtain an increase in the magnetic storage density. An additional problem encountered here is to also reduce the wear rate to the head gap. For these reasons, and because of their relationship to disk drive reliability, the current technology is limited by the achievable lowest flying height as a barrier to further increases in data storage density.
A proposed technique for providing a continuous lubricant supply for a magnetic media surface is shown in U.S. Pat. Nos. 2,969,435 and 3,005,675. In both patents a supply of lubricant is sprayed onto the disk or drum surface ahead of the area of contact between transducer head and media surface. This mode of placing a layer of lubricant on the media surface would not be compatible with the system of the present invention wherein a transducer is made to adjoin the media during relative motion therebetween with a separation of but 1 or 2 microinches. A later patent, U.S. Pat. No. 4,633,351 attempts to overcome some of the problems associated with the earlier patented techniques by spraying water or a volatile liquid solvent ahead of the transducer to create a thin liquid film between the head and the recording media surface.